Coaxial filament connector



June 24, 1958 s. J. CHERRY ET AL 2,840,748

COAXIL FILAMENT CONNECTOR .Filed Jum 26,1955

2 BY XII'ORNEY United States Patent O COAXIAL FILAMENT CONNECTOR Sidney John Cherry and William A. Gerard, Elmira, N. Y., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation f Pennsylvania Application June 26, 1953, SeralNo. 364,354

6 Claims. (Cl.

Our invention relates to electric discharge devices, and more particularly to high frequency, high power discharge devices. 4

It is an object of ourinvention to provide a new and improved electric discharge device.

lt is another object to provide an improved electric discharge device which is easily installed and removed from the cooperating circuit elements.

It is another object to provide an improved electric discharge device which permits ease of fabrication and assembly.

It is another object to provide an improved electric discharge device which will eliminate 4displacement of the cathode due to the expansion by the heating of the latter.

It is still a further object to provide an electric discharge device having an improved arrangement of electrode supports and electrode terminals.

These and other objects are effected by our invention as will be apparent from the following description taken in accordance with the accompanying drawing, throughout which like reference characters indicate like parts, and in which:

Figure l is `an elevational View, in cross section, of a preferred embodiment of our invention;

Fig. 2 is an elevational view of the cathode structure of the device of Fig. l, with parts broken away; and

Fig. 3 is a sectional view taken along the line IIl--III of Fig. 2.

Referring to the drawing and particularly to Fig. l, our improvements are illustrated in .a high power tetrode type tube. The tube comprises an envelope including -an anode 11 of suitable material in the for-m of a tubular member closed at one end. The closed end of the anode 11 is provided with a tubulation 12 for the evacuation of the envelope and is pinched off after exhaust and .a cap 13 is placed over the tubulation. The anode 11 is provided With a radiator core 14 surrounding the anode 11 and attached to the anode 11 by solder 15. Radiator fins 16 are attached to a part of the radiator core 14 and are utilized for air cooling of the tube. t

The lower end of the anode 11 has its outer surface slightly reduced in diameter to provide a positioning seat 17 for the inner edge of an anode ring 18 which is brazed to the anode 11. The outer edge of the anode ring 18 is sealed to the top of the envelope 10 las indicated at 19.

A screen 21 of cylindrical shape is disposed within and coaxial with the anode 11. A screen support 22 is provided in the form of a frustro-conical surface. The top of the screen support 22 has the same diameter as the screen 21 and lis attached to the bottom of the screen 21. The lower portion of the screen support 22 has a larger diameter than the top and has an outturned flange 23. A screen terminal 24 in the form of an annular member having an inturned ange 25 and coaxial with the screen 21 and -of greater diameter is positioned so that the tlange 23 of the screen support 22 may be at tached to the flange 25 o f the screen terminal 24. The

2 screen support 22 is connected to the 4screen terminal 24 by a terminal ring 26 which is clamped by bolts 27. The envelope 10 is also sealed to the ange 25 of the screen terminal 24 and encloses the screen support 22.

A grid 29 of cylindrical shape is disposed within and coaxial with the .screen 21. The grid 2,9 is supported by a cylindrical member 30 which has an outturned flange 31 at the bottom. The member 30 is of similar diameter and coaxial with the grid 29. The top of the grid support 30 is connected to the lower portion of the grid l29 while the ange 31 of the grid support 30 is connected to a grid terminal 32. The grid terminal is in the shape of a cylindrical member having an inturned flange 33 at its top. It is of smaller diameter than the screen terminal 24 and is disposed Within the screen terminal 24. The outturned flange 31 on the bottom of the grid support 30 is fastened to the inturned llange 33 of the grid terminal 32 by means of a clamp ring 34 and bolts 35. A preformed glass seal 36 is positioned between the screen terminal 24 and the grid terminal 32 with the grid terminal 32 extending below the Ascreen terminal."

A lamentary cathode 37 which is cylindrical in shape is positioned within and coaxial with the gri-d 29. The cathode wires 38 are supported at the top by support member 39 which is transverse to the axis ofthe tube and of disc-like shape with suitable filament holding means attached around the circumference. The cathode wires 38 are supported at the lbottom by lower and upper platforms 40 and 41 which are transverse to the aXisof the tube and disc-like in shape.

The lower and upper platforms 40 and 41 are formed with peripheral tabs or anchors 42 and 43 alternately arranged in a circle and which defines the circumference of the cathode 37. The tabs 43 are longer on the lower platform 40 than the tabs 42 on the upper platform 41 so that the tops of both sets of tabs 42 and 43 are at the same height along the axis of assembly. The cathode wires 38 are in the form of a hairpin loop. One end of each wire 38 is welded to a tab 42 and then the middle of the wire is fastened to the top support 39 and then the other end of the cathode wire 38 is welded to the tab 43. The cathode wires 38 may be held or retained by the top support member 39 in any suit-able manner.

The upper cathode support platform 41 is connectedfto the upper end of two upper support leads 45 and 46 which are parallel to the axis of the assembly and located at an equal distance from the axis and positioned apart. The lower end of the upper support leads 45 and 46 is connected to an upper cathode terminal 47. The upper cathode terminal is an inverted cupshaped metallic member having its cylindrical surface coax-ially'located with respect to the tube assembly. The upper cathode terminal is disposed within and the lower portion extends below the grid terminal 3 2 and a pre formedglass seal 4S is positioned between the grid terminal 32 and the upper cathode terminal 47 for sta bility and insulation. t v

The lower cathode platform 4Q is connected to the upper ends of two lower support leads 49 and Si? which are parallel to and of the same length as the two upper support leads 45 and 46 disposed 90 from the upper support leads 45 and 46 and at an equal distance from the axis as the support leads 45 and 4o. rl`he lower Vsupport leads` 49 and 59 pass through apertures 5l and 52 located in the top 55 of the upper cathode terminal 47 and are attached to a lower connector assembly 53. The lower Connector assembly 53 is composed of a lower cathode metallic terminal 56 in the formV of a cylinder, and a metallic flared connector 57 in the form of a cylindrical member having its lower portion brazed to the lower cathode terminal 56 and the upper portion having an outturned flange 58. The connector 57 is coaxially disposed within and extends below the upper cathode terminal 47. The two lower support leads 49 and 50 are connected to the ange '58 'of' the connector 57. A preformedglass seal 59 is positioned between the connector 57 and the upper cathode terminal 47 and rests on the lower terminal 56. The lower cathode terminal 56 may fbe of the same diameter as vthat of the`upper cathode terminal 47 and is`positioned` slightly lbelow the upper cathode terminal 47.

A cathode center support'rod 60 is'centrally located .with the assembly and has its lower end' embedded'within a vitreous material within the inside of the connector 57. The center support rod 60 carries on its upper end the top cathode support 39 mounted for axial movement. Thetop cathode support is insulated from the cathode center rod 60. The cathode wires 38 are tensioned by pusher sleeve 61 and a spring 62 surrounding center rod 60. A collar 63 is located near the lower part of the center rod 60 and the spring 62 is interposed between ,the collar 63 and the pusher sleeve 61. The upper part ofthe pusher sleeve 61 pushes against the bottom of the top cathode support 39. A centrally located aperture is provided in the top of upper cathode terminal 47 for passage of the center support rod 60. Y vOur invention, by providing for the equal length cathode support leads and equal distance of positioningv of the leads from the axis of the assembly, results in a ruggedA mechanical cathode connection and support and alleviates the expansion problem due to the heat of the cathode assembly. The simple tube assembly also permits the making of the metal-to-glass seals in a furnace in one operation. This insures the alignment and relative position of all the parts in the assembly. The design of the cathode assembly also permits the use of a larger diameter cathode terminal than that previously known which permits the use of a spring type socket contact.

Another advantage of the support leads 50, 46, 45 and .49 is that when they are heated, being the same length and subject to same temperature and temperature gradients, they will expand equally. It is also an advantage that the cooling on each set of support leads is equal. If the cathodeterminal is placed below the other in coaxial connecting type tube, some inequality in the length of the support structure must result. Our invention is such that inequalities occur in the cooler portion of the tube where the differences in expansion due to heating is small.

- While we have shown our invention in several forms, it lwill lbe obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit and upper terminal having a central aperture, a iirst set of 'i equal length support leads connecting said cathode vto said cup-shaped terminal, a tubular member having an outturned flange disposed within said'cup-shapedy terminal, a second set of equal length support leads of the same length as said first set extending through apertures provided in said cup-shaped terminal connecting said cathode to said tubular member and a solid cylindrical terminal connected to said tubular member of similar diameter as said cup-shaped terminal, said first and second set of support leads extending from said terminals to which they connected in the same direction.

2. An electron discharge device comprising an envelope enclosing a plurality of electrodes including at least a cathode, a support for said cathode including a first cylindrical member having an inturned flange on the top thereof, a second cylindrical member having an outturned flange on the top thereof, said second cylindrical member disposed within and extending below said first cylindrical member, a third cylindrical member attached to the lower end of said second cylindrical member and separated from said first cylindrical member, a center support rod for said cathode having its lower end embedded within said second cylindrical member, means attached to said center support member for tensioning said cathode, a iirst set of cathode support leads of equal length connected to said cathode and to the inturned flange of said first cylindrical member, and a second set of equal length support leads of the same length as said iirst set extending through apertures provided in said cup-shaped terminal and disposed at with respect to said first set of support leads, said second set of support leads being connected to said cathode and to the ange of said second cylindrical member, said first and second sets of supportleads extending from the terminal member to whichthe'y are vconnected in the same direction. 3. In ycombination withY an envelope of yan electron tube, a iirst solid cylindrical terminal, a second hollow cylindrical terminal, said ysecond terminal having an inturned flange at the'top thereof, said rst and second terminalslbeing coaxial and having the same diameter, said iir'sti'terminal bcinginsulated from and positioned below said second terminal, a cylindrical surface connector4 having'an outturned flange on the top thereof, said connector being'coaxially disposed within said second terminal with the lower end of said connector extending below said second terminal and connected to the top of saidiirst terminal, a seal between the lower portion of said first and second terminals, a plurality of equal length support leads vertically positioned coaxial with said first and second terminals and extending in the same direction from said terminals, a portion of said support leads being connected to the outturned flange of said connector and passing through apertures in the flange of said second terminal to a lower platform, the remainder of said support leads being connected to the inturned flange of said second terminal and to an upper platform, means of connecting filament ends to said upper and lower platform, and means for tensioning said filaments supported by said connector and electrically insulated therefrom.

4. In combination in an envelope of an electron tube, a cathode structure comprising a first terminal for said cathode in the form of a solid cylindrical member, a second terminal for said cathode in the form of a hollow cylindrical member having an inturned flange located at the top thereof, said tirst and second terminals being coaxial and substantially of the same diameter, said iirst terminal being insulated from and positioned below said second terminal, a hollow cylindrical connector member having an outturned ange on the top thereof, said connector being coaxially disposed within said second terminal, the lower end of said connector extending below said second terminal and being connected to said first terminal, a glass seal located between said first and second terminals, iirst and second support leads vertically positioned apart and at-equal distances from the axis of said tube, said iirst and second support leads being connected tov the outturned ange of said connector and passing through apertures in the inturned flange of said second terminal, third and fourth support leads vertically positioned v180 .apartv and located at the same distance from the axis and 90 apart with respect to said first and second' support leads and being of the same length as said first and second support leads, and means attached to the top of said support leads for attaching filaments.

5. A'support structure for a cylindrical cathode comprising a lower solid cylindrical terminal, a tubular member, an outturned ilange located at the top of said cylindrical member, said tubular member being coaxially disposed withrespect to said lower terminal and having its lower portion attached to the top of said lower terminal, an inverted cup shaped metallic upper terminal having the same diameter as said lower terminal and coaxially positioned with respect to said tubular member so as to enclose said tubular member with its lower portion positioned slightly above said lower terminal, a spacing ring of vitreous material interposed between said tubular member and said upper terminal and resting on the top of said lower terminal, a filament tensioning means having its lower portion imbedded within an electrical insulating material within said tubular member and its upper portion connected to a top cap of said cylindrical cathode, a first pair of equal length support leads connected to the outturned ilange of said tubular member and to a lower support platform for said cylindrical cathode, a second pair of support leads of the same length as said first pair connected to the top of said upper terminal and to an upper support platform for said cylindrical cathode, and tlamentary cathode wires having one terminal connected to said lower support platform and another terminal connected to said upper support platform and held in position by said top cap.

6. A support structure for a cylindrical fllamentary cathode comprising a lower cylindrical metallic terminal, a tubular connecting member having `an outturned flange near the top of said connector member, said connector member having its lower portion connected to the top of said lower terminal and coaxially positioned with respect to said lower terminal, an inverted cup like metallic upper terminal surrounding said connector and coaxially positioned above said lower terminal, a spacing ring of vitreous material interposed between said connecting member and said upper terminal and resting on the top of said lower terminal, a support rod having its lower portion imbedded in a vitreous material within said connecting member and having a sleeve and spring surrounding said support rod pressing against a top cap of said lilamentary cathode so as to tension the fllamentary members of said cathode, vertically positioned equal length support leads disposed at equal distances from said support rod and at equal distances from each other, an upper support platform having tabs located around its circumference for connection to tilamentary members of said cathode, alternate leads of said support leads having their lower portion connected to said upper terminal and upper portion connected to said upper support platform, a lower support platform having tabs located around its circumference for connection to ilamentary members of said cathode, the remaining of said support leads passing through apertures in said upper terminal and connecting said lower support platform to said connecting member.

References Cited in the iile of this patent UNITED STATES PATENTS 2,441,349 Eitel et al. May 1l, 1948 2,455,846 West Dec. 7, 1948 2,456,714 Law Dec. 21, 1948 2,542,639 De Walt Feb. 20, 1951 

